In a system with a single initiator node, and one or more memory-only 'target' nodes, the memory-only node(s) would fail to register their initiator node correctly. i.e. in sysfs:
# ls /sys/devices/system/node/node0/access0/targets/ node0
Where as the correct behavior should be:
# ls /sys/devices/system/node/node0/access0/targets/ node0 node1
This happened because hmat_register_target_initiators() uses list_sort() to sort the initiator list, but the sort comparision function (initiator_cmp()) is overloaded to also set the node mask's bits.
In a system with a single initiator, the list is singular, and list_sort elides the comparision helper call. Thus the node mask never gets set, and the subsequent search for the best initiator comes up empty.
Add a new helper to sort the initiator list, and handle the singular list corner case by setting the node mask for that explicitly.
Reported-by: Chris Piper chris.d.piper@intel.com Cc: stable@vger.kernel.org Cc: Rafael J. Wysocki rafael@kernel.org Cc: Liu Shixin liushixin2@huawei.com Cc: Dan Williams dan.j.williams@intel.com Signed-off-by: Vishal Verma vishal.l.verma@intel.com --- drivers/acpi/numa/hmat.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c index 144a84f429ed..cd20b0e9cdfa 100644 --- a/drivers/acpi/numa/hmat.c +++ b/drivers/acpi/numa/hmat.c @@ -573,6 +573,30 @@ static int initiator_cmp(void *priv, const struct list_head *a, return ia->processor_pxm - ib->processor_pxm; }
+static int initiators_to_nodemask(unsigned long *p_nodes) +{ + /* + * list_sort doesn't call @cmp (initiator_cmp) for 0 or 1 sized lists. + * For a single-initiator system with other memory-only nodes, this + * means an empty p_nodes mask, since that is set by initiator_cmp(). + * Special case the singular list, and make sure the node mask gets set + * appropriately. + */ + if (list_empty(&initiators)) + return -ENXIO; + + if (list_is_singular(&initiators)) { + struct memory_initiator *initiator = list_first_entry( + &initiators, struct memory_initiator, node); + + set_bit(initiator->processor_pxm, p_nodes); + return 0; + } + + list_sort(p_nodes, &initiators, initiator_cmp); + return 0; +} + static void hmat_register_target_initiators(struct memory_target *target) { static DECLARE_BITMAP(p_nodes, MAX_NUMNODES); @@ -609,7 +633,9 @@ static void hmat_register_target_initiators(struct memory_target *target) * initiators. */ bitmap_zero(p_nodes, MAX_NUMNODES); - list_sort(p_nodes, &initiators, initiator_cmp); + if (initiators_to_nodemask(p_nodes) < 0) + return; + if (!access0done) { for (i = WRITE_LATENCY; i <= READ_BANDWIDTH; i++) { loc = localities_types[i]; @@ -643,7 +669,9 @@ static void hmat_register_target_initiators(struct memory_target *target)
/* Access 1 ignores Generic Initiators */ bitmap_zero(p_nodes, MAX_NUMNODES); - list_sort(p_nodes, &initiators, initiator_cmp); + if (initiators_to_nodemask(p_nodes) < 0) + return; + for (i = WRITE_LATENCY; i <= READ_BANDWIDTH; i++) { loc = localities_types[i]; if (!loc)